1. Field of the Invention
The present invention relates to one pack type alicyclic epoxy resin compositions which can be cured at moderate, elevated temperatures and which have excellent storage stability at room temperature.
2. Description of the Background
It is known that alicyclic epoxy resins such as 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate have excellent weather resistance, and have good electrical insulation properties, thereby being useful as an electric insulating material, because the resins do not contain chlorine as an impurity. Generally speaking, bis-phenol type glycidyl ether epoxy resins are widely employed as electric insulating materials. However, the use of this material by the precision electronics industry poses some electrical related problems, because of the presence of residual chlorine as an impurity in the material. This impurity is conveyed from the raw materials. One-pack type epoxy resins are preferred to the conventional two-pack type epoxy resins, because the former cannot be misformulated and because they can be used continuously. A need therefore has continued to exist for an improved curing agent for a one-pack type epoxy resin.
It is pointed out that when alicyclic epoxy resins are cured, the same are combined with an acid anhydride as a latent curing agent. Acid anhydrides provide a long curing time. On the other hand, when the combination of an acid anhydride and a tertiary amine is used as the catalyst system for alicyclic epoxy resins, a resin composition of poor storageability results, and the cured resin exhibits a muddied appearance. A need therefore continues to exist for an improved catalyst system for one pack type epoxy resin compositions.